From Journal of the National Cancer Institute

From Gene Testing to the Bedside

Workshop Focuses on Future Strategies

Merrill Goozner

Abstract and Introduction

Introduction

In mid-June, the payment contractor for Medicare in California agreed to reimburse oncologists for using a diagnostic test that relies on gene expression profiling to classify undifferentiated metastatic tumors with unknown sites of origin. Such tumors occur in about 30,000 new cancer cases each year.

The Pathwork Diagnostics test, which the U.S. Food and Drug Administration approved in 2010, analyzes the expression patterns of more than 2,000 genes to determine which of 15 common cancers the unidentified tumors mimic. The payment decision in California, where the Pathwork lab is based and samples are sent, enables the test's wider use to aid in choosing treatment strategies in these situations.

A company-funded validation study that appeared in the January 2011 Journal of Molecular Diagnostics showed that the Pathwork® Tissue of Origin Test accurately identified tumors 88.5% of the time. It had only a 1% false-positive rate, the study said. A recent meta-analysis of immunohistochemistry (IHC) studies, which was also company-funded, showed that the traditional pathology method generated accurate diagnoses only two-thirds of the time.

And that's how company officials are marketing the test—as a better, and potentially less costly diagnostic tool than repeated immunohistochemistry and imaging tests. "That's the criteria for all diagnostic tests—that you accurately measure what you purport to measure," said David Henner, M.D., Ph.D., chief medical officer for Pathwork Diagnostics. "We're not a stand-alone diagnostic. We're an aid to the physician getting to the correct diagnosis."

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From Gene Testing to the Bedside: Abstract and Introduction